1. Field of the Invention
The present invention generally relates to the provision of haptic feedback in an electronic device, and more particularly, to an actuator for providing haptic feedback using an electro-active polymer, and electronic device therewith.
2. Description of the Related Art
A haptic feedback refers to a means of expressing information depending on a tactile sense and a skin contact of a user, which includes a force feedback function for remote controlling a robot arm. Recently, an effort has been made to use a haptic feedback as a means of notifying a user that a signal value of a key, which is selected by the user, is normally input when the user operates a touch panel as well as a simple vibration function of notifying the user of receiving a call in a portable terminal such as a cellular phone.
With the emergence of electronic devices having a touch panel for providing a full-browsing screen, an input unit such as a keypad, for inputting data is established in a button form or an icon form. When a user touches the input unit displayed on the touch panel screen, the input unit inputs a signal value allocated to a point by sensing the point that the user touches. However, an input method of touching the input unit displayed on the full-browsing screen has a problem in that the input unit cannot transfer a tactile recognition (i.e. a feeling of a click) to a user, differently from a conventional button type keypad. That is, in a case of a mechanical button input unit, such as a general dome switch and the like, when a user pushes the button type input unit, a feeling of a click is provided to the user. Accordingly, the user can tactually recognize an operation of a keypad. Therefore, although the user does not identify the input status through the screen of the touch panel, it is possible to recognize that numbers or letters which the user intends to input are input. However, it is difficult for the user to tactually identify an input of the numbers or letters by touch of the touch panel. Accordingly, an effort has been made to solve an inconvenience in that the user must identify a value input through the screen of the touch panel each time, by providing a haptic feedback function to the electronic device which has a touch panel type input unit mounted thereon. The haptic feedback function of the electronic device can be achieved by operating an actuator when the touch panel is operated.
A haptic feedback device is disclosed in Korean Patent Laid-open Publication No. 10-2011-0075714, and Korean Patent No. 10-1046017, both of which are incorporated herein by reference.
The publication and the patent disclose a DC motor actuator, a linear motor actuator, a piezo-actuator, a shape memory alloy actuator, an electro-active polymer actuator, and the like, as an actuator for providing a haptic feedback according to a touch of a touch panel. The electro-active polymer actuator has advantages in that it has a reaction speed more rapid than that of other actuators, can provide a large haptic feedback compared with an input electric power, is thin and light, and is cheap. The electro-active polymer actuator has flexibility, so there is an advantage in that it can be applied to a touch panel with a flexible display. However, although the electro-active polymer actuator has the above-mentioned advantages, there is a problem in that the electro-active polymer actuator has a structure and a circuit which are not completely developed and which is insufficient for a vibration actuator.